The Data Realms forums are full of great mods and i'm not sure where to start with the best one all i can say is i have troble downloading some of the mods i don't know if it's just me but if the file is from a certain site i can't get it.

TlenoTech. First version complete, unfortunately can't register on Data Realms forums for some reason, but I wrote an e-mail asking why, so I'll attempt to register and upload the mod ASAP as I'll get this issue solved!

My prefered mods are the ones that add addtional factions with their own styles and weapons, rather than more humans or completely overpowered factions (which most of the forum seems to be), and here they are:

The Mu-IlaakA army of red chitinous robots. They were a planned faction from the developers but have since been picked up by the modding community. They distinct themselves in being able to wield some pistols and smgs off-hand, like a shield. And unless their heads are destroyed it will seperate from the body and crawl off only to grow a new one.

Aco Delta CovenantAnother bunch of robots, this time with a more Warhammer 40k Tau feel. With powerful streamlined lasers, varying sizes of battlesuits and combat drones.

XenobiologyThis mod isn't a faction as so, but allows you to plant various hostile fauna when creating bases. The plants will be almost free, but in will in turn react to all actors that approaches them, and since they have a life of their own, with seed ejections etc you will sometimes need to cull the plants to keep the dangerous ones out of your base, giving them a vert unique role.